The present invention relates generally to the field of grass clipping catchers for lawnmowers and more specifically to cyclone separation grass clipping catchers.
A variety of grass clipping catchers have been developed over the years. A major design consideration for designing a grass catcher has been to devise a means for separating the cut grass clippings from the pressurized air flow which carries the clippings from the area of the mower blades to the clipping catcher. A common solution is to construct the clipping catcher with a material pervious to air but generally impervious to grass. However, generally, the lower the perviousness to grass a catcher has, the less the perviousness it has to air.
It is desirable to maximize the air flow through the mower and grass clipping catcher while maximizing the imperviousness of the catcher to grass clippings and other particles suspended in the air. However, air flow is impeded when filtering screens in the catcher are generally impervious to air, creating a significant back pressure of air. This back pressure, and concurrent reduced air flow, adversely affect the delivery of grass clippings from the mower to the catcher. Problems such as chute clogging and only partial pick up of grass clippings are more likely when there is reduced air flow. Thus, although highly impervious materials in the catcher improve loss of clippings and dust to the environment, they diminish the mechanical air flow delivery of grass clippings from the mower to the catcher. This problem is especially notable when grass clipping are to be caught in an impervious container such as a plastic grass bag.
One approach to this problem is disclosed in U.S. Pat. No. 3,987,606 to Evans. Evans uses a vortex flow of air in the grass catcher to separate the grass clippings from the air flow. The grass is centrifugally thrown against the walls of the catcher and precipitated towards the bottom of the catcher. The air flow exits upwardly, straight through the center of the vortex. In one embodiment, a screen is used to filter out grass clippings from the exiting air.
However, the approach used in Evans can be distinguished and improved upon. In the Evans approach, although much of the grass clippings precipitate due to the centrifugal action in the catcher, a substantial portion of clippings and associated dust still exhaust upwardly from the center of the vortex. This is true even when a screen is used to impede this clipping exhaust path. Furthermore, due to the geometry and structure of the delivery chute's interface with the catcher, the vortical flow inside the catcher is less than optimal. Also, the Evans approach requires separate means to support the housing which interfaces with the delivery chute. Finally, the round cross-section delivery chute in the Evans approach results in less than optimal vortical flow in the housing.
The disadvantages and inefficiencies of prior existing devices may be improved upon by a grass clipping catcher which takes advantage of a vortical flow separation of grass and air, while having improved aerodynamics in the flow of the grass clippings and air, baffling to prevent escape of grass clippings from the catcher, and a grass clipping vortical flow housing which is supported by the grass clipping catcher. As a result, the present invention improves upon reducing the unwanted escape of dust and other particulate matter flowing upwardly in the vortex and out of the catcher. The present invention also facilitates removal of the grass clipping container for simplified emptying.